Optical communication systems using for example, optical fiber as a transmission medium, have low loss and very high information carrying capacity. In practice, the bandwidth of optical fiber may be better utilized to increase the bandwidth of a communication system by transmitting many distinct channels simultaneously using different carrier wavelengths. In WDM (wavelength division multiplexed) networks, for example, multiple optical signals each at different wavelengths are combined and transmitted over an optical fiber. WDM systems therefore sometimes utilize multiple laser sources that coupled into a single optical fiber.